Plug and receptacle connector



A. l. APPLETON 3,046,515

PLUG AND RECEPTACLE CONNECTOR July 24, 19-62 Filed May 5, 1958 3 Sheets-Sheet 1 July 24, 1962 A. l. APPLETON PLUG AND RECEPTACLE CONNECTOR s Sheets-Shet 2 Filed May 5, 195a ENVEMTOK July 24', 1962 A. l. APPLETON 3,046,515

PLUG AND RECEPTACLE CONNECTOR Filed May 5, 1958 3 Sheets-Sheet 3 [law/11 g LI 1.! M-I I.

tv v l. Cflppl m r WI W/WMM; Ll fb 3,046,515 PLUG AND RECEPTACLE CONNECTOR Arthur I. Appleton, Northbrook, Ill. Appleton Electric (10., 1713 Wellington Ave., Chicago 13, Ill.)

Filed May 5, 1958, Ser. No. 732,861 7 (llaims. (Cl. 339-111) The present invention relates to electrical connectors and more particularly to plug and receptacle type electrical connectors for use in weather-proof and explosionproof installations.

It is the primary object of the present invention to provide an improved plug and receptacle connector of the above character having a multiplicity of contacts. Another object is to provide a multiple contact connector of the above type which incorporates arc extinguishing means so that it is useful in explosive atmospheres.

A further object of the present invention is to provide an improved electrical connector of the foregoing type which is of rugged construction, is simple and easy to manufacture and thus is economical to produce and which is simple to maintain and repair. More specifically, it is the object of the present invention to provide an electrical connector of the foregoing character which is light in weight, highly dielectric, and so constructed that either the plug or the receptacle can be used as the hot connection.

Still another object is to provide a connector which is easy to use and involves no complicated twisting and pushing or pulling procedures to effect explosion-proof operation, and which can be easily yet safely operated with the use of only one hand. A more detailed object of the present invention is to provide an improved electrical plug and receptacle type connector wherein the plug and receptacle are easily alined for connecting a 'large number of contacts with a minimum'of manipulations of the plug and wherein the plug is easily removed from the receptacle with due regard for extinguishing any arcs which may be formed before the plug and receptacle are completely separated.

Still another object of the present invention is to provide a connector which is compact and which takes up a minimum of space and at the same time embodies desired weather-proof and explosion-proof characteristics. A related object is to provide a compact plug and receptacle connector having the above features in which a series of contact groups can be alined one with the other while maintaining the desirable explosion-proof character as well as the other advantages described above.

Other objects and advantages of the present invention will become apparent as the following description proceeds, taken in connection with the accompanying drawings wherein:

FIGURE 1 is a sectional elevation view through a plug and receptacle illustrative of the present invention showing the plug completely inserted in the receptacle;

FIG. 2 is a section view similar to FIG. 1 but showing the plug separated from the receptacle;

FIG. 3 is a fragmentary view similar to FIG. 1 but showing the plug partially inserted in the receptacle;

FIG. 4 is a fragmentary view similar to FIG. 3 showing the plug inserted further within the receptacle but prior to the completion of contact therewith;

FIG. 5 is a section view taken substantially in the plane of line 55 of FIG. 1;

FIG. 6 is a section view taken substantially in the plane of line 66 of FIG. 4;

FIG. 7 is a perspective view of a plug illustrative of the present invention;

FIG. 8 is a perspective view of a receptacle illustrative of the present invention;

States Patent G ice FIG. 9 is an exploded fragmentary view of the re-' ceptacle contact assembly;

FIG. 10 is a perspective view of plug useful in a modified form of connector illustrative of the present invention;

FIG. 11 is a section view similar to FIG. 6 but showing the contact relationships in a plug and receptacle embodying a plug of the type shown in FIG. 10;

FIGS. 12 and 13 are section views similar to FIG. 11 but showing the plug and receptacle contacts coupled in alternate positions;

FIG. 14 is a fragmentary section view of another modified form of connector illustrative of the present invention showing a plug partially inserted and connected with a first set of receptacle contacts;

FIG. 15 is a fragmentary view similar'to FIG. 14 but showing the plug completely inserted to provide a second sequence of contacts; and

FIG. 16 is a framentary view of a polarizing slot on the plug shown in FIGS. 14 and 15.

Although certain illustrative modifications of plug and receptacle type connectors have been shown in the drawings and will be described below in considerable detail, it should be understood that there is no intention to limit the invention to the specific forms disclosed. On the contrary, the intention is to cover all modifications alternative constructions, equivalents and uses falling within the spirit and scope of the invention as expressed in the appended claims.

There is shown in the drawings (FIGS. 1-9) an electrical connector embodying the features of the present invention and comprising a plug 10 and receptacle 11 engageable by the plug for coupling a plurality of conductors carried in cables 12 and 13 in a selected sequence or arrangement and in an explosion-proof manner. Electrical connection between the plug Ill and the receptacle 11 is afforded by a plurality of contacts 16 on the plug engageable with a corresponding plurality of contacts 17 in the receptacle. the illustrative connector by inserting the plug '10 completely within the receptacle 11 and then rotating the former relative to the latter to bring the respective contacts 16, 17 into engagement.

In accordance with one aspect of the present invention, the plug and receptacle contacts 16 and 17 are, when the plug is inserted in the receptacle, isolated from the surrounding atmosphere by an arc extinguishing chamber which is of suificient extent to effectively eliminate any are and thereby prevent an explosive reaction of gases in the vicinity of the connector which may be initiated. by any are resulting when the contacts are separated. The are extinguishing action is accomplished by providing a smooth surface 19 on the plug closely fitting in snug sliding relation with a corresponding smooth surface 20 on the receptacle. These surfaces define, when the plug is inserted in the receptacle, a relatively long extremely thin annulararc extinguishing chamber extendingbetween the contacts and the outside atmosphere.

Accordingly, any are formed as the plug is rotated to Turning first to the plug 10 which carries the contacts 16 and is provided with the smooth surface 19 thereon,

\ it can be seen that it comprises a body 22 having an an- This engagement is accomplished in 'The contacts 16 extend V their contact faces flush with the inner sleeve surface 19 and located at the inner end of the chamber 24. The explosion-proof surface extends for a substantial distance between the contacts and the end of the plug.

For engagement with the conductors of the cable 12 the contacts 16 are provided, on the opposite side of the body 22, with appropriate terminal clamps 25. These terminal connections 25 are sealed within a housing 26 and to this end the housing 26 is provided with internal threads 27 engaged with external threads 28 surrounding the body. A positive seal is provided between the housing and the body by a gasket or washer 29 and a setscrew 39 holds the pieces tightly together.

In order to receive and sealingly engage the cable 12, the housing 26 is provided with a cable receiving opening 32 defined by an externally threaded sleeve 33 for receiving a sealing nut 34. Surrounding the cable '12 and compressed within the opening 32, which is slightly tapered, is a resilient sealing bushing 35. The bushing is wedged tightly in the opening 32 by means of an annular shoulder 36 extending inwardly from the nut 34 and engaging its free end. Rotation of the nuton the housing sleeve 33 compresses the bushing tightly around the cable thereby providing an effective seal against the entrance of moisture and the like into the housing.

For receiving the sleeve portion 23 of the plug there is provided in the recpetacle an annular chamber 40 surrounding the explosion-proof surface 20 and the receptacle contacts 17. For defining this chamber, as well as for supporting the contacts 17, the receptacle comprises a cylindrical body portion 41 having on its outer peripheral surface the explosion-proof surface 20 and carrying on said peripheral surface adjacent the outer end apertures 42 in which are mounted the contacts 17. At its inner end adjacent the surface 20, the cylindrical body is formed with a radially outwardly extending annular flange 44 supporting an annular sleeve member 45 surrounding the body 41 and extending slightly beyond the end surface thereof. The inner surface 46 of the sleeve 45 closely surrounds the inserted plug sleeve 23 thereby providing a further bar to the entrance of explosive gases, moisture or the like to the contacts when the plug and receptacle are joined.

In order to positively seal the connector against the entrance of moisture there is desirably provided an O-ring sealing member 47 on the external surface of the plug engageable in sealing relation with the internal surface 46 of the receptacle. When the plug is inserted in the annular receptacle chamber 40, the combination of the sealing ring 47, the narrow spacing between the sleeve surfaces, and the explosion-proof surfaces 19 and 29 provide an effectively sealed arc extinguishing and moistureproof chamber for the contacts.

For purposes of connecting the receptacle contacts to the cable conductors 13, a plurality of metallic conductors 50 extend axially through the body from the rear end to the terminal apertures 42. At their rearmost ends the conductors 50 are provided with terminal clamps 51 seated in recesses 52 defined in the rear portion of the body and receiving the conductor wires 13.

In order that the receptacle contacts 17 be easily replaceable when they become worn or pitted, they are mounted in the receptacle so as to be removable therefrom. To this end the conductors 50 do not extend into the aperture 42 but terminate at the edge thereof, and the contacts 17 are provided with a leg 54 fitted in an axially extending groove 55 beneath the conductors 50. The contacts are formed in a generally S-shaped configuration, having an upper leg for contact with the plug contacts and the lower leg 54 for engagement with the receptacle conductors 50 (FIG. 9). The end of the leg 54 is desirably bent back upon itself to provide a tight wedging engagement and thus a good electrical connection with the conductor 50.

The contacts 17 are held in their apertures 42 and in contact with the conductors 50 by means of an end plate 56 of insulating material having a diameter substantially equal to the diameter of the cylinder and secured to the latter by means of a screw 58 or the like for easy removal. When the insulated end plate 56 is fastened in place on the cylindrical body 41 the outer ends of the contact 17 are protected leaving only the surface portion thereof exposed along the periphery of the receptacle body for engagement by the plug contacts 16.

The contacts 17 are desirably formed to extend slightly outwardly into the annular chamber 40 so that a wiping engagement is obtained with the plug contact 16 as the plug is rotated, thus insuring a good electrical contact between the two contacts.

The receptacle terminals are sealed within a conduit box housing or the like, shown in phantom at 60. For mounting the receptacle on such a box, a mounting flange 61 is provided on the outer sleeve 45 with holes 62 therein for receiving suitable fasteners '(FIG. 8).

In use the plug is inserted within the receptacle in a manner insuring that the explosion-proof surfaces 19 and 20 are in the desired juxtaposed relation before the plug contacts 16 are engaged with the receptacle contacts 17. To this end the plug sleeve 23 is inserted into the annular chamber 40 in the receptacle with the plug contacts 16 circumferentially displaced relative to the receptacle contacts (FIG. 6). When the plug is completely inserted (FIG. 4) it is then rotated to bring to the con- 7 tacts 16 and 17 together with a wiping action (FIG. 5).

The foregoing sequence of operation is assured by the provision of a radially inwardly extending pin 65 on the inner surface of the receptacle sleeve and a cooperating polarizing slot 66 on the outer peripheral surface of the plug sleeve 23 (FIGS. 2 and 6). The slot 66 is oriented relative to the pin 65 to provide for the insertion of the plug into the receptacle with the plug contacts 16 circumferentially spaced relative to the receptacle contacts 17. When the plug has been completely inserted the plug can be rotated, the polarizing groove being formed with a circumferentially extending leg portion 67. When the plug is in its rotated position the polarizing groove 67 engages the pin 65 and thereby prevents the plug from being withdrawn directly from the receptacle.

In order to provide for an explosion-proof withdrawal of the plug, it must first be rotated to remove the pin 65 from the groove 67. In this step the contacts 16 and 17 are separated and the are if any is extinguished in the extremely narrow annular arc extinguishing chamber defined between the closely juxtaposed surfaces 19 and 20. When the contacts have been separated, the plug can be withdrawn from the receptacle with the polarizing pin 65 sliding out of the groove 66.

If desired, one of the contacts on the plug can make immediate engagement with a receptacle contact upon insertion of the plug for the purpose of providing a ground connection. To this end one of the receptacle contacts 17' extends circumferentially around the cylindrical body 41 (FIGS. 5 and 6).

For preventing the entrance of moisture or dirt into the receptacle when the plug has been removed, the receptacle is desirably provided with a swinging cap 69 hinged between depending cars 70 on the receptacle sleeve 45. A torque spring (not shown) is mounted on the hinge pin 71 and biases the cap 69 to a closed position against the end of the sleeve 45 thereby completely enclosing the receptacle contacts. To improve the seal between the cap 69 and the sleeve 45 a gasket 72 is provided on the surface of the former. For a similar purpose, a rubber cap or the like (not shown) may be provided for enclosing the end of the plug when it is not in use.

In order to provide a selection between alternative sets of contacts, the contacts are arranged as shown in FIGS. 10 through 13 for providing one set of connections upon insertion and rotation of the plug in one direction and a second set of connections upon rotation of the plug in the opposite direction. To this end the plug and receptacle are constructed as describedabove, with the exception of the placement of the contacts on either one or both of the plug and receptacle members. In the modification shown in FIGS. through 13, the receptacle is constructed as described above and the plug is provided with two spaced contacts 16a and 16b for each receptacle contact 17.

So as to permit the plug to be rotated in one of two selected directions, the polarizing groove 66 extends into the center of a circumferentially extending groove portion defined by groove legs 67a and 67b. The plug is inserted into the receptacle with the groove 66 guiding the pin 65 and with the contacts 16a and 16b spaced from receptacle contacts 17. Rotation of the plug in one direction with receptacle pin 65 guided in polarizing groove 67a will cause one set of contacts 16a to engage the receptacle contacts 17 (FIG. 12). Similarly, rotation of the plug in the opposite direction with pin- 65 extending into polarizing groove 67b will bring the other set of plug contacts 16b into engagement with the receptacle contacts 17 (FIG. 13). To provide a continuous ground connection one of the receptacle contacts 17 may be provided with an extended circumferential surface for engaging the corresponding plug ground contacts 16a and 16b as the plug is being inserted.

It will be understood that any desired number of contacts. can be provided on both the receptacle and the plug to provide for two separate combinations of connections. While one set of plug contacts has been shown as being inoperative when the plug is rotated to a selected position, a second corresponding set of contacts can be provided on the receptacle for engaging these plug contacts, thereby completing two separate circuits at the same time. While only a limited number of contacts have been shown in the drawings for convenience in illustration, it will-be understood that there is no such limitation in actual practice, the number of contacts being determined as desired by the number of conductors in the cables to be employed and the number of circuits to be completed.

In a further modified form of the-present invention provision is made for a predetermined sequence of connection between two sets of axially disposed contacts in the receptacle 11. In this modification (illustrated in FIGS. 14 and 16), the plug 10 and receptacle 11 are constructed as described above with the exception of the provision of a first set of contacts 17a on the cylindrical receptacle body 41 axially spaced from a second set of contacts 1712. These receptacle contacts 17a and 17a being axially spaced, the plug contacts 16 will engage the outer receptacle contacts 17:: first and, upon further insertion, will engage the second set of contacts 1717. In the modification shown in the drawings the polarizing groove (FIG. 16) provides for the insertion of the plug sleeve 23 part way into the annular receptacle opening 40 with the pin 65 being guided in the polarizing groove 66. Upon rotation of the plug, with the pin'guided in the circumferentially extending polarizing groove 67, the firstset of receptacle contacts 170: will be engaged with the plug contacts 16 (FIG. 14). Upon further insertion of the plug with the pin 65 guided in an axially extending polarizinggroove 670, the second set of receptacle contacts 17b will be engaged by the plug contacts 16 (FIG. If, in this latter engagement it is desired that the plug contacts 16 do not engage the first set of recetpacle contacts 17a the former may be notched as shown in phantom at 75 in FIG. 15. Alternatively, two separate sets of plug and receptacle contacts may be employed to provide for a plurality of separate connections.

In order to provide replaceable contacts in the modifications shown in FIGS. 14 and 15, the cylindrical receptacle body 41 is formed in two parts with a removable portion 76 secured to the main body portion 41 by means of the insulated plate fastening screw 58 which extends through the removable body portion 76 and is threadably engaged with the cylindrical body 41. The conductors 50a and 53b corresponding respectively to the contacts 17:: and,

of connections between the plug and receptacle contact I V is provided. Both the plug and the receptacle can be formed with any desired number of contacts, being limited only by the size of the connector desired. Accordingly, three or more series of contacts can be provided on the receptacle with the plug being designed for successive insertions and rotations. e

In all of the foregoing modifications, there is provided an annular explosion-proof chamber defined by the smooth closely fitting surfaces 19 and 20 on the plug 10 and receptacle 11 respectively. Any are formed duringthe making or breaking of the contacts is eifectively extinguished before the plug can be withdrawn from the receptacle, explosive gases are excluded from the arc extinguishing chamber, and any dangerous explosive reaction is prevented.

I claim as my invention:

.1. In an electrical connector, the combination comprising a receptacle comprising an elongated cylindrical contact support having a smooth external surface,-said cylindrical support defining at its outer end a plurality of circumferentially spaced recesses opening to the side and end thereof, a plurality of conductors having clamping terminals on their inner ends and extending through said therefrom in coextensive spaced coaxial surrounding rela-- tion with said support, said support and said sleeve member defining an annular plug receiving socket, a plug receivable in said socket comprising a -body supporting an annular elongated contact support member having a smooth internal wall surface and insertable into said socket with said internal wall surface inclose coextensive proximity with the external surface of said cylindrical contact support, a plurality ofplug contacts having an outer end extending through said body and recessed in,

the inner end of said internal wall surface adjacent the body and circumferentially spaced corresponding to said receptacle contacts for engagement therewith upon the insertion of said annular member into the socket and subsequent rotation thereof, said plug contacts having clam-ping terminals on their inner ends, a housing surrounding said terminals and sealingly engaging said body,

said smooth internal wall surface of said'annular contact support member having a radial dimension relative to the radial dimension of the smooth external wall surface of the cylindrical contact support such that the plug slides snugly around said cylindrical contact supportover a substantial axial distance for providing anelongated, thin,

arc extinguishing chamber therewith, and means providing for a multi-step delayed withdrawal of said plug from said receptacle including initial separation of said plug and receptacle contacts by relative rotation of said plug and receptacle and subsequent axial separation of said plug and receptacle whereby any explosion within said chamber will be extinguished before the plug and receptacle are completely separated.

2. In an electrical connector, the combination comprising a receptacle comprising an elongated cylindrical contact support having a smooth external surface, said cylindrical support defining at its outer end a plurality of" circumferentially spaced recesses opening to the side and end thereof, a plurality of conductors, a plurality of receptacle contacts mounted in said recesses, means fixed to the outer end of said support for holding said receptacle contacts in said recesses and insulating the same against endwise electrical contact, an annular sleeve member surrounding said support in coextensive spaced coaxial relation therewith, said support and said sleeve member defining an annular plug receiving socket, a plug receivable in said socket comprising a body supporting an annular elongated contact support member having a smooth internal wall surface and insertable into said socket with said internal wall surface in close coextensive proximity with the external surface of said cylindrical contact support, a plurality of plug contacts having an outer end extending through said body and recessed in the inner end of said internal wall surface adjacent the body and circumferentially spaced corresponding to said receptacle contacts for engagement therewith upon the insertion of said annular member into the socket and subsequent rotation thereof, said smooth internal wall surface of said annular contact support member having a radial dimension relative to the radial dimension of the smooth external wall surface of the cylindrical contact support such that the plug slides snugly around said cylindrical contact support over a substantial axial distance for providing an elongated, thin, arc extinguishing chamber therewith, and means providing for a multi-step delayed withdrawal of said plug from said receptacle including initial separation of said plug and receptacle contacts by relative rotation of said plug and receptacle and subsequent axial separation of said plug and receptacle whereby any explosion within said chamber will be extinguished before the plug and receptacle are completely separated.

3. In an electrical connector, the combination comprising a receptacle comprising an elongated cylindrical contact support having a smooth external surface, said cylindrical support defining at its outer end a first set of circumferentially spaced recesses opening to the side and end thereof, and defining at a portion spaced from the outer end a second set of circumferentially spaced recesses opening to the side thereof, a plurality of conductors having clamping terminals on their inner ends and extending through said support into said recesses, first and second sets of receptacle contacts mounted respectively in said first and second sets of recesses in electrical engagement with said conductors, means fixed to the outer end of said support for holding said receptacle contacts in said first set of recesses and insulating the same against endwise electrical contact, a radially extending flange on the inner end of said support and spaced a substantial distance from said recesses and receptacle contacts, an annular sleeve member fixed at its inner end to said flange and projecting therefrom in coextensive spaced coaxial surrounding relation with said support, said support and said sleeve member defining an annular plug receiving socket, a plug receivable in said socket comprising a body supporting an annular elongated contact support member having a smooth internal wall surface and insertable into said socket with said internal wall surface in close coextensive proximity with the external surface of said cylindrical contact support, a plurality of plug contacts having an outer end extending through said body and recessed in the inner end of said internal wall surface adjacent the body and circumferentially spaced corresponding to said sets of receptacle contacts for engagement with said first sets of receptacle contacts upon partial insertion of said annular member into the socket and subsequent rotation thereof, and with said second set of receptacle contacts upon further insertion of said annular member into the socket, said plug contacts having clamping terminals and sealingly engaging said body, said smooth internal wall surface of said annular contact support member having a radial dimension relative to the radial dimension of the smooth external wall surface of the cylindrical contact 0 support such that the plug slides snugly around said cylindrical contact support over a substantial axial distance for providing an elongated, thin, arc extinguishing chamber therewith, and means providing for a multi-step delayed withdrawal of said plug from said receptacle including initial separation of said plug and receptacle contacts by relative rotation of said plug and receptacle and subsequent axial separation of said plug and receptacle whereby any explosion within said chamber will be extinguished before the plug and receptacle are completely separated.

4. In an electrical connector, the combination comprising an elongated cylindrical contact support having a smooth external surface, a plurality of circumferentially spaced receptacle contacts recessed in said external surface adjacent the outer end of said contact support, means fixed to the outer end of said support for retaining said receptacle contacts and insulating the same against endwise electrical contact, an annular sleeve member fixed at its inner end to said support at a point spaced a substantial distance from said receptacle contacts and projecting therefrom in coextensive spaced coaxial surrounding relation with said support, said support and said sleeve member defining an annular plug receiving receptacle, an annular elongated contact support plug having a smooth internal wall surface and insertable into said receptacle with said internal wall surface in close coextensive proximity with the external surface of said cylindrical contact support, a plurality of plug contacts recessed in the inner end of said internal wall surface adjacent the body and circumferentially spaced corresponding to said receptacle contacts for engagement therewith upon the axial insertion of said plug into said receptacle and subsequent rotation thereof, and polarizing means cooperable between said annular sleeve member and said plug for guiding the latter for axial insertion into said receptacle and for subsequent rotation to engage the plug contacts with the receptacle contacts.

5. In an electrical connector, the combination comprising an elongated cylindrical contact support having a smooth external surface, a first set of circumferentially spaced receptacle contacts recessed in said external surface adjacent the outer end of said contact support, a second set of circumferentially spaced receptacle contacts recessed in said external surface adjacent the outer end of said contact support intermediate the contacts of said first set, means fixed to the outer end of said support for retaining said receptacle contacts and insulating the same against endwise electrical contact, an annular sleeve member fixed at its inner end to said support at a point spaced a substantial distance from said receptacle contacts and projecting therefrom in coextensive spaced coaxial surrounding relation with said support, said support and said sleeve member defining an annular plug receiving receptacle, an annular elongated contact support plug having a smooth internal wall surface and insertable into said receptacle with said internal wall surface in close coextensive proximity with the external surface of said cylindrical contact support, a single set of plug contacts recessed in the inner end of said internal wall surface adjacent the body and circumferentially spaced corresponding to said receptacle contacts for engagement with said first set of receptacle contacts upon the axial insertion of said plug into said receptacle and subsequent selected rotation thereof in one direction and with said second set of receptacle contacts upon selected rotation in the opposite direction, and polarizing means cooperable between said annular sleeve member and said plug for guiding the latter for axial insertion into said receptacle and for subsequent rotation to engage the plug contacts with the selected set of receptacle contacts.

6, In an electrical connector, the combination comprising an elongated cylindrical contact support having a smooth external surface, a first set of circumferentially spaced receptacle contacts recessed in said external surface adjacent the outer end of said contact support, a second set of circumferentially spaced receptacle contacts recessed in said external surfaces at a point spaced from said first set toward the inner end of said contact support, means fixed to the outer end of said support for retaining said first set of receptacle contacts and insulating the same against endwise electrical contact, an annular sleeve member fixed at its inner end to said support at a point spaced a substantial distance from said receptacle contacts and projecting therefrom in coextensive spaced coaxial surrounding relation with said support, said support and said sleeve member defining an annular plug receiving receptacle, an annular elongated contact support plug having a smooth internal wall surface and insertable into said receptacle with said internal wall surface in close coextensive proximity with the external surface of said cylindrical contact support, a plurality of plug contacts recessed in the inner end of said internal wall surface adjacent the body and circumferentially spaced corresponding to said first set of receptacle contacts for engagement therewith upon partial axial insertion of said plug into said receptacle and subsequent rotation thereof, and to said second set of receptacle contacts for engagement therewith upon further axial insertion into said receptacle, and polarizing means cooperable between said annular sleeve member and said plug for guiding the latter for axial insertion into said receptacle and for subsequent rotation to engage the plug contacts with the receptacle contacts.

7. In an electrical connector, the combination comprising an elongated. cylindrical contact support having a smooth external surface, a first and second axially spaced set of circumferentially spaced receptacle contacts recessed in said external surface adjacent the outer end of said contact support, means fixed to the outer end of said support for retaining said receptacle contacts and 10 insulating the same against endwise electrical contact, an annular sleeve member fixed at its inner end to said support at a point spaced a substantialdistance from said receptacle contacts and projecting therefrom in coextensive spaced coaxial surrounding relation with said support, said support and said sleeve member defining an annular plug receiving receptacle, an annular elongated contact support plug having a smooth internal Wall 6111',

face and insertable into said receptacle with said internal wall surface in close coextensive proximity with the external surface of said cylindrical contact support, a first and second set of plug contacts recessed in the inner end of said internal wall surface adjacent the body and circumferentially spaced corresponding respectively to said first and second sets of receptacle contacts for engagement therewith upon the axial insertion of said plug into said receptacle and subsequent rotation thereof, and polarizing means cooperable between said annular sleeve member and said plug for guiding the latter for axial insertion into said receptacle and for subsequent rotation to selectively engage respective plug contacts with corresponding receptacle contacts.

References Cited in the file of this patent 

